The present invention relates to an endoscope apparatus, an information storage device, an image processing method, and the like.
An improvement in detection accuracy of a lesion in a body cavity has been desired in the field of endoscopic diagnosis. An endoscope that includes a zoom optical system that improves the detection accuracy by magnifying the difference in tissue between a lesion area and a normal area at a magnification almost equal to that of a microscope (hereinafter may be appropriately referred to as “zoom endoscope”) has been known.
A zoom endoscope may be configured to achieve a magnification of several ten to several hundred times. The fine structure of the mucosal surface layer and the blood vessel distribution pattern can be observed by utilizing such a zoom endoscope in combination with a stain solution or a blood vessel-enhanced (weighted) image obtained using narrow-band illumination light (hereinafter may be referred to as “NBI image”). It is known that a lesion area and a normal area differ in the above pattern, and the above pattern has been used as a diagnostic criterion for lesions.
However, the depth of field significantly decreases during zoom observation along with an increase in magnification as compared with normal observation. In this case, it is difficult to continuously position the end of the insertion section (hereinafter may be referred to as “scope” or “imaging section”) of the endoscope within the in-focus range relative to the object, and considerable skill is required to continuously obtain (observe) an in-focus image.
If it takes time to position the scope during zoom observation in order to obtain an in-focus image, the entire diagnosis time necessarily increases. As a result, the doctor gets tired, and the burden imposed on the patient increases.
The above problem may be solved by the method disclosed in JP-A-10-165365 that sets an area that is considered to be outside the depth-of-field range within one image, and performs a defocus restoration process to implement an increase in depth of field. The method disclosed in JP-A-10-165365 detects distance when observing a tubular cavity using the endoscope, and performs the defocus restoration process on an area within a given distance range.
The above problem may also be solved by the method disclosed in JP-A-2003-140030 that performs an autofocus process during zoom observation.